The use of amalgam in dentistry has recently come under severe criticism, with the media identifying amalgam as a serious health hazard. Reports of mercury toxicity have made the public very sensitive and very concerned about the potential dangers and risks that may be associated with this material. Without conclusive evidence of the concentration of mercury vaporized from the surface of dental amalgam, the public will continue to be swayed by these media reports of mercury poisoning. The proposed research outlines a series of fundamental experiments designed to accurately determine the amount of mercury at the amalgam surface and the vapor emitted from this surface as a function of loading. The techniques that will be used are Auger spectroscopy, x-ray photoelectron spectroscopy, residual gas analysis, piezoelectric quartz crystal sensor, and scanning electron microscopy. The combination of these techniques provides a comprehensive study of mercury release from dental amalgam. The major advantage of this approach is that all measurements will be performed in an ultra-high vacuum chamber, providing a stable environment and thus reducing or eliminating many of the factors that are a source of uncertainty in other methodologies. The specific goals of this project are: 1) to establish the best surface spectroscopic technique for quantitative and reliable measurement of mercury at the amalgam surface; 2) to study mercury vapor released from amalgam during loading; 3) to study the diffusion of mercury through dental amalgam by examining the relationship between mercury release and the ratio of grain boundary to the amalgam alloy surface area.